The present invention relates to a metal laminate gasket with narrow and wide flange portions alternately arranged to each other to securely seal around a hole in an internal combustion engine.
A metal gasket or metal laminate gasket is installed between two engine parts to securely seal around sealing holes. In the engine, since high pressure and temperature are formed in or around the sealing holes, there have been proposed many sealing mechanisms.
In the engine, high temperature and pressure are generally formed in a cylinder bore. Therefore, in a cylinder head gasket, bolts for connecting a cylinder head and a cylinder block are arranged around the cylinder bore to secure seal around the cylinder bore.
In this case, if high tightening pressures are applied immediately outside the cylinder bore, the cylinder bore may deform due to the high tightening pressures applied from the bolts. Therefore, in the engine, the high tightening pressures should not be simply applied around the cylinder bore.
In one type of the convention gaskets, the gasket is formed of two or three plates, such as U.S. Pat. No. 4,898,396 and No. 5,213,345. A first metal plate is turned around a hole or cylinder bore to be sealed to form a flange disposed above a base portion of the first metal plate, and a second metal plate is located on the base portion. The second metal plate may be situated between the flange and the base portion, or may not overlap the flange. A bead or sealing device is formed on one of the first and second plates to surround the cylinder bore.
In this gasket, when the gasket is tightened with high tightening pressures by bolts, portions on the flange near the bolts receive high tightening pressures from the bolts. Namely, high tightening pressures are applied at the portions near the bolt holes around the cylinder bore, while the low tightening pressures are formed in other portions around the cylinder bore. Thus, when the tightening pressures around the sealing hole or cylinder bore are considered as a whole, the high and low tightening pressures are formed around the cylinder bore. Namely, the tightening pressures are not properly distributed around the cylinder bore to possibly cause leakage from the cylinder bore or deformation of the cylinder bore.
In order to securely seal around the hole, parts of the bead away from the bolt holes may be arranged to provide high surface pressure, such as disclosed in U.S. Pat. No. 4,759,556. On the other hand, a spring constant of one bead may be partly changed to securely seal around a hole, such as disclosed in U.S. Pat. No. 5,269,541.
The conventional gaskets operate properly, as intended. However, it is still required to improve a sealing quality and prevent deformation of the cylinder bore.
The present invention has been made in view of the conventional gaskets, and an object of the invention is to provide a metal laminate gasket which can securely seal around a hole to be sealed.
Another object of the invention is to provide a metal laminate gasket as stated above, wherein influences by local tightening pressures by bolts are minimized.
A further object of the invention is to provide a metal laminate gasket as stated above, wherein an area around the hole to be sealed can receive an equal tightening pressure.
Further objects and advantages of the invention will be apparent from the following description of the invention.